Modelling of soil salinity and halophyte crop production
Vermue, E. ; Metselaar, K. ; Zee, S.E.A.T.M. van der - \ 2013
Environmental and Experimental Botany 92 (2013). - ISSN 0098-8472 - p. 186 - 196.
gewasproductie - bodemfactoren - zoute gronden - halofyten - bodemwater - verzilting - modellen - crop production - edaphic factors - saline soils - halophytes - soil water - salinization - models - salt tolerance - root water - growth - plants - irrigation - stress - extraction - simulation - wheat - transpiration
In crop modelling the soil, plant and atmosphere system is regarded as a continuum with regard to root water uptake and transpiration. Crop production, often assumed to be linearly related with transpiration, depends on several factors, including water and nutrient availability and salinity. The effect of crop production factors on crop production is frequently incorporated in crop models using empirical reduction functions, which summarize very complex processes. Crop modelling has mainly focused on conventional crops and specific plant types such as halophytes have received limited attention. Crop modelling of halophytes can be approached as a hierarchy of production situations, starting at the situation with most optimal conditions and progressively introducing limiting factors. We analyze crop production situations in terms of water- and salt limited production and in terms of combined stresses. We show that experimental data as such may not be the bottleneck, but that data need to be adequately processed, to provide the basis for a first analysis. Halophytic crops offer a production perspective in saline areas, but in other areas long-term use of low quality irrigation water for halophyte production can result in serious soil quality problems. An overview is given of potential problems concerning the use of (saline) irrigation water, leading to the conclusion that soil quality changes due to poor quality water should be considered in determining the areas selected for halophyte growing.
Impact analysis of drought and salinity on grassland production in the Netherlands using historical and future climate data
Kroes, J.G. ; Supit, I. - \ 2011
Agriculture, Ecosystems and Environment 144 (2011)1. - ISSN 0167-8809 - p. 370 - 381.
atmospheric co2 - carbon-dioxide - elevated co2 - dry-matter - root water - crop - yield - model - simulation - temperature
The coupled SWAP–WOFOST model was used to study the effects of increasing salinity of groundwater, drought and water excess on grass production in The Netherlands. WOFOST simulates crop growth and SWAP simulates transport of water, solutes and heat in the vadose zone. The model was tested using several datasets from field experiments. We applied the models at regional scale where we quantified the impact of various groundwater salinity levels on grass growth and production using historical weather data (1971–2000). The salt concentrations in the subsoil were derived from the National Hydrological Instrument. The results show that salinity effects on grass production are limited. In wet years the excess rainfall will infiltrate the soil and reduce salt water seepage. In a next step we used future weather data for the year 2050, derived from 3 Global Circulation Models. From each model we used data from two CO2emission scenarios. As expected higher temperatures increased drought stress, however, the production reduction as a result of salt water in the root zone is limited. Salt stress mainly occurred when irrigation was applied with saline water. The increased CO2concentration in combination with the limited drought stress resulted in increasing simulated actual and potential yields. Overall conclusion for grassland in The Netherlands: drought stress is stronger than stress caused by water excess which on its turn is stronger than salinity stress. Future water demand for irrigation may increase by 11–19% and result in water scarcity if water supply is insufficient.
Matric potential measurements by polymer tensiometers in cropped lysimeters under water-stressed conditions
Ploeg, M.J. van der; Gooren, H.P.A. ; Bakker, G. ; Rooij, G.H. de - \ 2008
Vadose Zone Journal 7 (2008). - ISSN 1539-1663 - p. 1048 - 1054.
time-domain reflectometry - root water - soil - extraction - responses - drought - systems - maize
In many regions of the world, plant growth and productivity are limited by water deficits. As a result of more frequent and intense droughts, the area of land characterized as very dry has more than doubled since the 1970s. Consequently, understanding root water uptake under water-stressed conditions is gaining importance. The performance of a recently developed polymer tensiometer (POT) designed to measure matric potentials down to ¿1.6 MPa was evaluated and compared with volumetric moisture content measurements in dry soil. Three irrigation intensities created severe, intermediate, and no water stress conditions in lysimeters with growing maize (Zea mays L.) plants. By monitoring matric potentials using POTs, levels of local water stress in our experiments were better defined. When the defined stress levels were reached, volumetric moisture measurements for this particular loam soil were below 0.1, thus less informative compared with matric potential measurements. The observed matric potential profiles indicate significant root water uptake between 0.3- and 0.5-m depth in the later growth stages under water-stressed conditions. The temporal pattern of matric potential profiles reflected changing root water uptake behavior under dry conditions. As the total soil water potential is a direct indication of the amount of energy required by plants to take up water, POTs may contribute to quantifying root water uptake in dry soils.